Implement mimetype sniffing for extensions.

chrome/browser/download/download_manager.h

Index: chrome/browser/download/download_manager.h
diff --git a/chrome/browser/download/download_manager.h b/chrome/browser/download/download_manager.h
index f1b10302c46b254cf21ebda3f6b2154324a8cff5..f39308efbfc8f68b3532d6cb0c6d1189052f57f9 100644
--- a/chrome/browser/download/download_manager.h
+++ b/chrome/browser/download/download_manager.h
@@ -109,6 +109,7 @@ class DownloadItem {
                int path_uniquifier,
                const GURL& url,
                const GURL& referrer_url,
+               const std::string& mime_type,
                const FilePath& original_name,
                const base::Time start_time,
                int64 download_size,
@@ -186,6 +187,7 @@ class DownloadItem {
   void set_path_uniquifier(int uniquifier) { path_uniquifier_ = uniquifier; }
   GURL url() const { return url_; }
   GURL referrer_url() const { return referrer_url_; }
+  std::string mime_type() const { return mime_type_; }
   int64 total_bytes() const { return total_bytes_; }
   void set_total_bytes(int64 total_bytes) { total_bytes_ = total_bytes; }
   int64 received_bytes() const { return received_bytes_; }
@@ -238,6 +240,9 @@ class DownloadItem {
   // The URL of the page that initiated the download.
   GURL referrer_url_;
 
+  // The mimetype of the download
+  std::string mime_type_;
+
   // Total bytes expected
   int64 total_bytes_;